Copy Files with FSCopyObject?

I copy any kind of file to local and remote disks using
FSCopyObject routines, a bit customized. Recently I discovered that
FSAllocateFork returns an error -34 (diskFull) when copying files bigger
than 2GB over my local net. Instead the destination disk has enough free
space. As written athttp://lists.apple.com/archives/Carbon-dev/2005/Dec/msg00031.html
I can quite omit FSAllocateFork, so I did. I copied a file over a local net
and checked the final size and it is equal to the source file size. The file
copied was a 7GB dmg file, and it works properly, I can mount the disk and
work with all the files therein. So it seems to work well.

I would like to know, could this omission cause some trouble when copying
other kind of files? E.g. Does it work with old MacOS 9 application files,
with data and resource forks, etc. etc.?

Also, I noted that the Finder is much faster than my routines when copying
this and other files. Do you know some new API that could copy files to any
local and remote disk (to any disk format as well as the Finder)?
Some year ago I used copyPath and it had some trouble with remote servers
and with large files so I am a little bit afraid to use it again. I also
used ditto but I recall it had some limitation too.
Can someone point me to the best solution? Thanks.